Re: [PATCH] libelf: check decompressed ZSTD size

[Mark Wielaard <mark@klomp.org>]

Hi Aleksei,

On Thu, Nov 23, 2023 at 03:31:47PM +0000, Aleksei Vetrov wrote:
> Decompression functions like __libelf_decompress_zlib check that
> decompressed data has the same size as it was declared in the header
> (size_out argument). The same check is now added to
> __libelf_decompress_zstd to make sure that the whole allocated buffer is
> initialized.
> 
>     * libelf/elf_compress.c (__libelf_decompress_zstd): Use return value
>       of ZSTD_decompress to check that decompressed data size is the
>       same as size_out of the buffer that was allocated.

Thanks, this makes sense. If the decompressed size isn't what was
encoded in the Chdr then we could reduce the size of the d_buf/d_size,
but that probably is not what the user expects. Flagging it as
bad/inconsistent data makes sense. Especially since we do the same for
zlib compressed data.

Pushed,

Mark